Handling array value in JS

Question

I have a problem with my arrays in JavaScript. I can't seem to get the value correctly.

I create my array in PHP like this:

$data = Array();        
$get = mysql_query("SELECT x,y,sid FROM table WHERE uid='1'");
    while($row = mysql_fetch_assoc($get)){
        $data[$row['x']] = Array();
        $data[$row['x']][$row['y']] = $row['sid'];
        }
$data = json_encode($row)

EDIT The json_encode comes out as "false" /EDIT

I then assigned this $data to a JS variable as sdata.

So then i try to get the value in JS but its not working. I get an undefined error.

This is my Javascript:

var i = 1;
var j = 5;
    if(sdata["x"] == i && sdata["y"] == j){
    alert(sdata["x"]["y"]["sid"]);
            }

Its meant to alert me the value of "sid" but i get: Undefined

Any ideas where my mistake is?

you have to use sdata.x, sdata.y and sdata.sid and not sdata[x] etc. Please read my answer below and please let me know if it works for you — dAm2K
– dAm2K, Commented Mar 14, 2012 at 0:23

Erik Kettenburg · Accepted Answer · 2012-03-14 01:04:38Z

2

Given your json

alert(sdata["x"]["y"]["sid"]);

should be

alert(sdata["sid"]);

as the json encoded data you show is only a one dimensional array

EDIT

If your json comes out as false, that's a different story:

$data = json_encode($row);

Should be inside your loop, for good practice, and if you're just encoding the $row why even bother with

    $data[$row['x']] = Array();
    $data[$row['x']][$row['y']] = $row['sid'];

Otherwise try

print_r($row);

within your while statement and make sure your expected result is coming through from mysql in the first place.

EDIT

If you are trying to get the $data variable in json then use

$data = json_encode($data);

outside of your loop.

EDIT

JSFiddle to return sid for given x and y - I'm sure it can be done in a cleaner way, but it's a start http://jsfiddle.net/HWByj/

var sdata = {"4":{"4":"1"},"7":{"1":"0"}};
var i = 4;
var j = 4;

if(typeof sdata[i] != 'undefined')
{
    if(typeof sdata[i][j] != 'undefined')
    {
        alert(sdata[i][j]); //gives you the value of sid
    }
}

edited Mar 14, 2012 at 1:04

answered Mar 14, 2012 at 0:01

Erik Kettenburg

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8 Comments

Sir Over a year ago

But there could be many rows of data thats why its in a while loop it just so happens in this situation i had one row of data but there could be numerous

Erik Kettenburg Over a year ago

See my last edit - json_encode doesn't support multi-dimensional arrays

Crashspeeder Over a year ago

@ErikKettenburg json_encode works just fine with multi-dimensional arrays. Where did you get that from?

Erik Kettenburg Over a year ago

@Crashspeeder you're completely right - I've removed that comment entirely

Sir Over a year ago

this fixed the array issue - i now have : {"4":{"4":"1"},"7":{"1":"0"}} But i need to get the value of "1" for example if x is 4 and y is 4 .. which is where im stuck :) As my JS showned above im lost how to check

|

abe · Accepted Answer · 2012-03-14 00:01:42Z

2

In your example, you only need:

alert(sdata["sid"]);

answered Mar 14, 2012 at 0:01

abe

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Comments

Crashspeeder · Accepted Answer · 2012-03-14 00:06:40Z

1

If your json_encode() is returning false then make sure you're getting data back from the query. Additionally, you're not doing anything with $data, you're doing the json_encode() on $row, which will give you a different structure than I believe you're expecting.

answered Mar 14, 2012 at 0:06

Crashspeeder

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Comments

Tim Gautier · Accepted Answer · 2012-03-14 15:50:01Z

1

It looks to me like your problem is here:

$data = json_encode($row)

I think you want this:

$data = json_encode($data);

You're looping through the rows and putting data in $data, but then you're encoding the $row variable. You're also using that $row variable to drop out of the while loop, so $row is probably null when you encode it. That's why it's coming out as false.

edited Mar 14, 2012 at 15:50

answered Mar 14, 2012 at 0:03

Tim Gautier

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Comments

dAm2K · Accepted Answer · 2012-03-14 00:19:42Z

0

You have to use sdata.x, sdata.y and sdata.sid since the returned json is not an associative array but it's an object.

Try with this piece of js code:

function myobjtool(myobj, i, j) {
        // alert("myobj: " + myobj.x);
        if(myobj.x == i && myobj.y == j) {
                alert(myobj.sid);
        }
}

myobj = {"x":"4","y":"4","sid":"1"}
myobjtool(myobj, 4, 4)

edited Mar 14, 2012 at 0:19

answered Mar 14, 2012 at 0:14

dAm2K

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